db.execute
db.execute allows the user to execute SQL statements.
If parameters for database connection are already set with db.connect, they are taken as default values and do not need to be specified each time.
If you have a large number of SQL commands to process, it is much much faster to place all the SQL statements into a text file and use db.execute’s input file parameter than it is to process each statement individually in a loop. If multiple instruction lines are given, each SQL line must end with a semicolon.
Please see the individual sql driver pages for how to create a new database.
Create a new table with columns ’cat’ and ’soiltype’:
echo ’create table soils (cat integer, soiltype varchar(10) )’ | db.execute
Create a new table using a file with SQL statements:
db.execute driver=odbc database=g60test input=file.sql
Insert new row into attribute table:
echo "INSERT INTO nobugs (id,name,east_gb,north_gb) values (30,’Ala’,1657340,5072301)" | db.execute
Update attribute entries to new value based on SQL rule:
echo "UPDATE roads SET travelcost=5 WHERE cat=1" | db.execute
Update attribute entries to new value based on SQL rule:
echo "UPDATE dourokukan SET testc=50 WHERE testc is NULL" | db.execute
Delete selected rows from attribute table:
echo "DELETE FROM gsod_stationlist WHERE latitude < -91" | db.execute
Add new column to attribute table:
echo "ALTER TABLE roads ADD COLUMN length double" | db.execute
Drop table (not supported by all drivers)
echo "DROP TABLE fmacopy" | db.execute
Update attribute with multiple SQL instructions in file (e.g., file.sql, instruction line must end with a semicolon):
UPDATE roads SET travelcost=5 WHERE cat=1;
UPDATE roads SET travelcost=2 WHERE cat=2;
cat file.sql | db.execute
db.columns, db.describe, db.drivers, db.droptable, db.login, db.select, db.tables, GRASS SQL interface
CERL
Last changed: $Date: 2007/05/17 08:55:11 $
Full index